arXiv subjects

Boyan Kostadinov

Publications and source records attributed to Boyan Kostadinov.

4 recordsLinked to original sources

arXiv2026

Central polynomials of minimal degree for matrices

Formanek made the conjecture that the minimal degree of the central polynomials for the $n\times n$ matrix algebra over a field of characteristic 0 is $(n^2+3n-2)/2$ and this is true for $n\leq 3$. For $n=4$ there are examples of central polynomials of degree $13=(4^2+3\cdot 4-2)/2$ and we do not know whether there are central polynomials of lower degree. In this paper we discuss methods for searching for central polynomials of low degree and prove that the algebra of $4\times 4$ matrices does not have central polynomials in two variables of degree $\leq 12$. As a byproduct of our computations we obtain that this algebra does not have also polynomial identities in two variables of degree $\leq 12$.

math.RA↗

arXiv2023

Noncommutative invariants of dihedral groups

We consider the 2-generated free metabelian associative and Lie algebras over the complex field and the invariants of the dihedral groups of finite order acting on these algebras. In the associative case we find a finite set of generators of the algebra of invariants. In the Lie case, when the algebra of invariants is not finitely generated, we give a minimal system of generators of the invariants in the commutator ideal as a module of the algebra of the invariants in the polynomial algebra in two variables. In both associative and Lie cases we compute the Hilbert series of the algebras of invariants.

math.RA↗

arXiv2020

A Diophantine transport problem from 2016 and its possible solution in 1903

Motivated by a recent Diophantine transport problem about how to transport profitably a group of persons or objects, we survey classical facts about solving systems of linear Diophantine equations and inequalities in nonnegative integers. We emphasize on the method of Elliott from 1903 and its further developed by MacMahon in his ``$Ω$-Calculus'' or Partition Analysis. As an illustration we obtain the solution of the considered transport problem in terms of a formal power series in several variables which is an expansion of a rational function of a special form.

math.NT↗

arXiv2016

Cocharacters of polynomial identities of block triangular matrices

We give an algorithm which calculates the generating function of the cocharacter sequence of the polynomial identities of the algebra of upper block triangular (p+2q) x (p+2q) matrices over a field of characteristic zero with diagonal consisting of p copies of 1 x 1 and q copies of 2 x 2 matrices. We have found the explicit form of the multiplicities and their asymptotic behaviour for small values of p and q.

math.RA↗